Themes of Biology

Section 1.1

Characteristics of Living Organisms

Biology is the study of life

Zoology is a branch of biologyZoologists study the animal kingdom

All living things share certain characteristics

Cellular Structure and Function

Cells are highly organized, tiny structures with thin coverings called membranes.

All living things are made of one or more cells.

A cell is the smallest unit capable of all life functions.

Unicellular organisms – one generalized cell Multicellular organisms – many specialized

cells … ALL animals are multicellular

Reproduction

Reproduction is the process by which organisms make more of their own kind from one generation to the next.

Two types of reproduction: Sexual – involves 2 parents Asexual – involves 1 parent

Metabolism

Metabolism is the sum of all the chemical reactions carried out in an organism.

Almost all energy used by living organisms is originally captured from sunlight.

Energy is transferred from organism to organism in the food chain

Homeostasis

Homeostasis is the maintenance of a stable internal conditions in spite of changes in the external environment.

An organism unable to balance its internal conditions with its environmental conditions could become ill and die.

Heredity

Heredity is the passing of traits from parent to offspring.

The basic unit of heredity is called a gene. Genes are coded in a molecule called

deoxyribonucleic acid (DNA) A change in the DNA of a gene is called a

mutation. Most mutations are harmful, but some mutations can help an organism survive.

Evolution

Evolution is defined as change in the inherited characteristics of species over generations.

A species is a group of genetically similar organisms that can produce fertile offspring.

Natural selection is the process in which organisms with favorable traits are more likely to survive and reproduce.

Interdependence

The organisms in a biological community live and interact with other organisms.

Ecology is the branch of biology that studies the interactions of organisms with one another and with the nonliving part of their environment.

Organisms are dependent on each other and on their environment.